1. Field of the Invention
The present invention relates to a liquid crystal display device and a manufacturing method therefor.
2. Description of the Related Art
Liquid crystal display devices are display devices, which include a liquid crystal display panel in which a liquid crystal layer is provided between a pair of substrates. The liquid crystal display devices are widely used as, for example, a liquid crystal display device for a liquid crystal television set or a personal computer, a liquid crystal display device for a cell-phone unit, and the like.
Liquid crystal display devices of this type are display devices, in which a display region of the liquid crystal display panel is constituted by an assembly of a plurality of pixels, and which display images or videos of, for example, letters, numbers, figures, and pictures by the plurality of pixels (dots). Such a display method is generally called a dot matrix method.
The dot matrix method is classified into two types depending on a drive method of the pixels, that is, a simple matrix type (also called as a passive matrix type) and an active matrix type. The simple matrix type refers to a type in which a voltage is selectively applied to electrodes for pixel formation formed on each substrate to drive a predetermined pixel. Meanwhile, the active matrix type refers to a type in which active elements (also called as switching elements) for pixel selection are formed on one substrate, and the active elements are turned ON/OFF to drive a predetermined pixel. The latter active matrix type particularly exhibits excellent performance, for example, in contrast performance and fast display performance, and hence the active matrix type has become the mainstream of the drive method of the pixels in the liquid crystal display device.
Further, examples of operation mode of a liquid crystal layer in a liquid crystal display device of this kind include a twisted nematic (TN) mode, a super twisted nematic (STN) mode, a vertical alignment (VA) mode, an optically compensated birefringence (OCB) mode, an in-plane switching (IPS) mode, and a fringe field switching (FFS) mode.
In particular, in a large-sized liquid crystal display device such as a liquid crystal television set, high contrast and high viewing angle properties are required, and for the achievement thereof, development of the IPS mode and the FFS mode has been progressed. Those needs are also required in a small-sized liquid crystal display device such as a cell phone, and hence development of IPS mode or FFS mode products has been accelerated.
Further, many of the recent cell-phone units or car navigation systems load a function of, for example, allowing a user to view a television program or playing a video. Also in the small-sized liquid crystal display device used in those portable electronic devices, in order to realize long period use, power saving has been required as a new need.
Note that, in Japanese Patent Application Laid-open No. 2001-209036, there is described a liquid crystal display device including: a first substrate including a plurality of pixel switching elements and a plurality of pixel electrodes; and a second substrate on which a counter electrode is formed, in which between the first substrate and the second substrate, a polymer network is formed at a border portion of adjacent pixels.